x86: adjust which Dwarf2 register numbers to use

Consumers can't know which execution mode is in effect for a certain
piece of code; they can only go from object file properties. Hence which
register numbers to encode ought to depend solely on object file type.

In tc_x86_frame_initial_instructions() do away with parsing a register
name: We have a symbolic constant already for the 64-bit case, and the
32-bit number isn't going to change either. Said constant's definition
needs moving, though, to be available also for non-ELF. While moving
also adjust the comment to clarify that it's applicable to 64-bit mode
only.

2 files changed, 9 insertions, 23 deletions

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 93de0b6..fecb25a 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -3275,7 +3275,7 @@ md_begin (void)
       operand_chars[(unsigned char) *p] = *p;
   }
 
-  if (flag_code == CODE_64BIT)
+  if (object_64bit)
     {
 #if defined (OBJ_COFF) && defined (TE_PE)
       x86_dwarf2_return_column = (OUTPUT_FLAVOR == bfd_target_coff_flavour
@@ -5438,7 +5438,7 @@ ginsn_dw2_regnum (const reg_entry *ireg)
   if (ireg->reg_num == RegIP || ireg->reg_num == RegIZ)
     return GINSN_DW2_REGNUM_RSI_DUMMY;
 
-  dwarf_reg = ireg->dw2_regnum[flag_code >> 1];
+  dwarf_reg = ireg->dw2_regnum[object_64bit];
 
   if (dwarf_reg == Dw2Inval)
     {
@@ -17663,7 +17663,7 @@ tc_x86_parse_to_dw2regnum (expressionS *exp)
       if ((addressT) exp->X_add_number < i386_regtab_size)
 	{
 	  exp->X_add_number = i386_regtab[exp->X_add_number]
-			      .dw2_regnum[flag_code >> 1];
+			      .dw2_regnum[object_64bit];
 	  if (exp->X_add_number != Dw2Inval)
 	    exp->X_op = O_constant;
 	}
@@ -17673,22 +17673,7 @@ tc_x86_parse_to_dw2regnum (expressionS *exp)
 void
 tc_x86_frame_initial_instructions (void)
 {
-  static unsigned int sp_regno[2];
-
-  if (!sp_regno[flag_code >> 1])
-    {
-      char *saved_input = input_line_pointer;
-      char sp[][4] = {"esp", "rsp"};
-      expressionS exp;
-
-      input_line_pointer = sp[flag_code >> 1];
-      tc_x86_parse_to_dw2regnum (&exp);
-      gas_assert (exp.X_op == O_constant);
-      sp_regno[flag_code >> 1] = exp.X_add_number;
-      input_line_pointer = saved_input;
-    }
-
-  cfi_add_CFA_def_cfa (sp_regno[flag_code >> 1], -x86_cie_data_alignment);
+  cfi_add_CFA_def_cfa (object_64bit ? REG_SP : 4, -x86_cie_data_alignment);
   cfi_add_CFA_offset (x86_dwarf2_return_column, x86_cie_data_alignment);
 }
 
diff --git a/gas/config/tc-i386.h b/gas/config/tc-i386.h
index b93799a..7aae7a3 100644
--- a/gas/config/tc-i386.h
+++ b/gas/config/tc-i386.h
@@ -396,6 +396,11 @@ extern void tc_x86_parse_to_dw2regnum (expressionS *);
 #define tc_cfi_frame_initial_instructions tc_x86_frame_initial_instructions
 extern void tc_x86_frame_initial_instructions (void);
 
+/* DWARF register number of the frame-pointer register in 64-bit mode.  */
+#define REG_FP 6
+/* DWARF register number of the stack-pointer register in 64-bit mode.  */
+#define REG_SP 7
+
 #define md_elf_section_type(str,len) i386_elf_section_type (str, len)
 extern int i386_elf_section_type (const char *, size_t);
 
@@ -425,10 +430,6 @@ extern void x86_cleanup (void);
    R15 (15).  Use SCFI_CALLEE_SAVED_REG_P to identify which registers
    are callee-saved from this set.  */
 #define SCFI_MAX_REG_ID 15
-/* Identify the DWARF register number of the frame-pointer register.  */
-#define REG_FP 6
-/* Identify the DWARF register number of the stack-pointer register.  */
-#define REG_SP 7
 /* Some ABIs, like AMD64, use stack for call instruction.  For such an ABI,
    identify the initial (CFA) offset from RSP at the entry of function.  */
 #define SCFI_INIT_CFA_OFFSET 8